Single-skin hull vessels are usually used to transport liquid cargo, such as gasoline, crude oil and various other liquid chemicals. If the hull is breached from an accident, the leakage of liquid into the surrounding sea may cause pollution.
Because of the international furor created by oil spills, various schemes have been proposed to minimize the danger of leakage from oil carriers. Usually, the solution lies in a double hull vessel whose design is such that if an accident impairs the structure of the outer hull, the inner hull can be expected to retain its integrity and prevent leakage of the liquid cargo held therein.
Unfortunately, because the center of gravity of the load is higher in double hull vessels than in single hull vessels, double hull vessels are less stable. Even if only a few of the compartments of a double hull vessel are breached, depending upon the subdivision arrangement, the resulting imbalance of the load might capsize the vessel, and the whole vessel might be lost.